Burner for use with fluid fuels

ABSTRACT

Burner for fluid fuels comprises a plurality of juxtaposed tubular modules each of which has external outlet surfaces at one end, external closure surfaces at the other end with a waist in between. At least some of the outlet surfaces have projections. The tubular modules cooperate so that the waists form a fuel chamber, adjacent closure surfaces mate to form fueltight joints, and the protruding areas of the outlet surfaces hold apart other areas of adjacent outlet surfaces to form fuel outlet passages. Fuel passes into the fuel chamber and thence via the fuel outlet passages to the combustion zone where it burns with air which enters the combustion zone via the bores of the modules.

United States Patent 1111 3, 23,735

[72] lnventors Denis H. Desty [56] References Cited y l i UNITED STATES PATENTS g": s 1,575,653 3/1926 Sonner 239/450 x 21 A I No 3 1,626,047 4/1927 Morley 239/552 x E f 22 1970 2,443,101 6/1948 Flynn et al. 239/555 x I 9 [45] Patented Dec. 21, 1971 Primary ExaminerLloyd L. King [73] Assignee The British Petroleum Company Limited Attorney-Morgan, Finnegan, Durham 8!. Pine London, England [32] Priority Jan. 23, 1969 [33] Gun Britain ABSTRACT: Burner for flu1d fuels comprises a plurality of 31 3,793 9 juxtaposed tubular modules each of which has external outlet surfaces at one end, external closure surfaces at the other end with a waist in-between. At least some of the outlet surfaces [54] BURNER FOR USE WITH FLUID FUELS have projections. The tubular modules cooperate so that the 8 Claims, 10 Drawing Figs. waists form a fuel chamber, adjacent closure surfaces mate to form fueitight joints, and the protruding areas of the outlet [52] Cl surfaces hold apart other areas'of adjacent outlet surfaces to [51] In nosb I06 fonn fuel outlet passages. Fuel: passes into the fuel chamber [50] i 239/425 5 and thence via the fuel outlet passages to the combustion zone 424 where it burns with air which enters the combustion zone via the bores of the modules.

I 1 V l j l I ,40 r I 75 I 12 l II I J- J uL l 1- I I1 J I I II I H I I1 II l L I l I BURNER FOR USE WITH FLUID FUELS This invention relates to a burner for use with fluid fuels, i.e. a burner suitable for use with liquid and gaseous fuels.

The specification of our copending application U.S. Ser. No. 694,319, filed Dec. 28, l967, now U.S. Pat. No. 3,504,994, granted Apr. 7, I970, describes and claims (inter alia) a burner for fluid fuels which comprises a plurality of combustion air tubes which pass through a fuel chamber and the walls of the combustion air tubes cooperate to form fuel outlet passages, the parts being arranged so that, in the use of the burner, the combustion air tubes convey air and the fuel outlet passages convey fuel to a combustion zone so as to maintain combustion. This invention relates to a specific construction of the burners described in U.S. Pat. No. 3,504,994.

According to this invention a burner for fluid fuels which comprises a plurality of juxtaposed tubular modules each of which has external outlet surfaces at one end, external closure surfaces at the other end with a waist in between, the said tubular modules cooperating so that:

i. the waists form a fuel chamber,

ii. adjacent closure surfaces mate to form fueltight joints,

and iii. protruding areas of the outlet surfaces hold apart nonprotruding areas of adjacent outlet surfaces so as to form fuel outlet passages, whereby, in the use of the burner, fuel passes into the fuel chamber and thence via the fuel outlet passages, to the combustion zone where it burns with air which enters the combustion zone via the bores of the modules.

The external cross sections of the modules at the inlet and closure surfaces are conveniently conformable polygons e.g. regular hexagons, rectangles, equilateral triangles and particularly squares.

Three configurations are particularly suitable for the outlet surfaces, these will hereinafter be identified as studed configurations, concave configurations and corrugated configurations.

In the case of a studed configuration the protruding areas take the form of studs which project from nonprotruding areas.

In the case of a concave configuration the protruding areas occur where three or more tubes are in juxtaposition, e.g. at the corners of polygonal tubes.

In the case of a corrugated configuration the outlet surfaces have a series of protruding and nonprotruding areas. This has the effect of producing tubes between the protruding areas.

(Note that not all the outlet surfaces need to have protruding areas. For example satisfactory results are obtained with polygonal tubes when half the outlet surfaces are without protruding areas.)

Conveniently the burner also comprises a surround within which the modules are mounted. Preferably the surround comprises a fuel channel for conveying fuel around and into the fuel chamber.

The bores of the modules correspond to the bores of the combustion air tubes of the burners described in U.S. Pat. No. 3,504,994 and they provide a low resistance passage for combustion air into the combustion zone. In order to achieve this low resistance it is desirable that the bore of each module has a minimum area of cross section of at least 0.01 cm.

The interstitial space between the modules, i.e. the space formed by the cooperation of the waists, provides a low resistance to the flow of fuel across the cross section of the fuel chamber thereby encouraging an even distribution of fuel.

The burners according to this invention are particularly suitable for use with gaseous fuels and in such cases the fuel outlet passages should be sufficiently narrow to provide an outlet resistance which is high in comparison with the internal resistance to flow across the fuel chamber. This encourages a uniform supply of fuel gas to the combustion zone. The burner will also work on vaporizable liquid fuels such as kerosene and for this application high-resistance fuel outlet passages are not necessary.

In order for burning to occur the fuel and the air must mix and it is particularly desirable that this mixing should take place by a diffusion mechanism. In order to achieve this it is necessary that the diffusion path be sufiiciently small and for this reason it is desirable that the cross-sectional area of the bore at the mouth of each module shall be less than 1.0 cm.

U.S. Pat. No. 3,504,994 states that it is desirable that the bores of the combustion air tubes account for at least 25 percent, preferably at least 50 percent, of the surface area of the burner adjacent to the combustion zone.

The invention will now be described by way of example with reference tothe diagrammatic drawings accompanying the instant specification in which:

FIG. I is a longitudinal cross section through a single module,

FIGS. 2-8 illustrate various arrangements for the outlet passages,

FIG. 9 is a vertical cross section through a complete burner,

FIG. 10 is a top view of a complete burner.

The module shown in FIG. I has a venturi-shaped bore 10 which conveys combustion air in the finished burner. At both ends of the module the external shape is that of a right-square prism forming closure surfaces 11 at one end and outlet surfaces 12 at the other with a waist 13 in between. The outlet surfaces 12 have protruding areas 14 (which may take the form of spacer studs).

FIGS. 2-8 show various arrangements for the formation of the fuel outlet passages. FIGS. 2-5, 7 and 8 are plan views showing nine modules because this number is sufficient to illustrate central, edge and comer positions; the bottom righthand tube is displaced to show the arrangement of the protruding areas 14. The fuel outlet passages are indicated by the numeral 15. The relative dimensions of the drawings are distorted to enable the various integers to be shown clearly. (Typical dimensions would be 6.3 mm. for the side of the external square and 0.25 mm. for the width of the gap).

As shown in FIG. 2 there is a centrally positioned spacer stud on each side of the module; the spacer studs of the central module are marked 14a in FIG. 2. These spacer studs project 0.125 mm. from the face and they engage with one another to give 0.25 mm. slits. 1

As shown in FIG. 3 each module has only two spacer studs situated on adjacent sides; the spacer studs of the central module are labeled 14b. These studs project 0.25 mm. from the face and they engage with a studless face to give gaps 0.25 mm. wide.

In the arrangement shown in FIG. 4 each module has four spacer studs situated accntrally on each face; the studs of the central module are labeled 14c. Each stud projects 025 mm. from its face and, as can be seen from FIG. 4, each stud engages with one face of an adjacent module to define gaps 0.25 mm. wide.

None of the arrangements shown in FIGS. 24 offers any great advantage over the others but the following comments are relevant:

In any one construction all the modules are identical. The arrangement of FIG. 3 requires correct orientation of each tube, i.e. with studs down and to the right as shown in the drawing.

The arrangement of FIG. 2 requires the engagement of studs half the thickness ofthe slit. This tends to increase inaccuracies. I

The arrangement of FIG. 4 uses full-sized studs and avoids the need for orientation but the use of two studs in each slit tends to obstruct the fuel exit passages more than one stud.

FIG. 5 shows a portion of a burner in which the outlet surfaces have a concave configuration. The tubes have protruding areas 14d at each corner and the faces are concave between so as to form the fuel outlet passages 15.

FIGS. 6-8 show corrugated outlet surfaces. FIG. 6 is a side view which shows that there are 10 protruding areas 14c per side and that these form channels connecting to the waist portion 13.

FIGS. 7 and 3 show the juxtaposition of corrugations to form the fuel outlet passages 15. ln FIG. 7 the corrugations occur on all sides of each module, in FIG. 8 on only two sides of each module (i.e. only half the outlet surfaces are corrugated).

FIG. 9 shows a longitudinal cross section through a burner which consists of a large number of modules situated inside a surround 17. This drawing shows how the waists of adjacent modules cooperate to form a fuel chamber 16 (which is continuous throughout the burner since-the vertical cross section at right angles is identical although the number of modules may be different).

Thesurround 17 comprises a fuel channel 18 which surrounds the fuel chamber 16 and an inlet pipe 19 to allow entry of the fuel gas. The figure also shows the formation of fuel outlet channels as described in greater detail with reference to FIGS. 2, 3 and 4 and the formation of fluidtight joints 20 by the cooperation of the closure surfaces 11 of the individual modules.

FIG. 10 is a plan view of the top face of the burner showing how all the modules are enclosed within the surround 17. We have obtained satisfactory operation of a burner when the modules were held entirely by the pressure exerted by the surround 17, i.e. no form of adhesive was used. It is emphasized that not only were the modules held in place but there was no escape of fuel gas between the closure surfaces. However this burner was only intended for laboratory test and in a commercial burner it would be desirable to secure the closure surfaces by means of a suitable adhesive. As the passage of combustion air through the bores of the modules ensures efficient cooling the temperature of the closure surfaces does not rise substantially above ambient. This makes it possible to use a low temperature adhesive or, in other words, techniques such as soldering, brazing and welding are not necessary.

We claim:

1. A diffusion flame burner for fluid fuels which burner comprises a plurality of juxtaposed individual tubular modules each of which has a. external outlet surfaces at one end for forming fuel outlet passages at said one end with external outlet surfaces of adjacent modules, b. external closure surfaces at the other end for forming fueltight joints at said other end with external closure surfaces of adjacent modules,

c. a reduced diameter portion between the external outlet surfaces and the external closure surfaces of the module, providing a waist for forming a fuel chamber with the waists of adjacent modules, and

d. a bore for conducting combustion air only through the module out of contact with fuel in said chamber from a combustion air inlet zone at said other end to a combustion zone at said one end, at least some of the external outlet surfaces of the module having protruding areas for engaging opposing areas of the external outlet surfaces of an adjacent module, and the said tubular modules cooperating so that:

i. the waists form a continuous fuel chamber around said modules between the external outlet surfaces and the external closure surfaces of said modules,

ii. opposing closure surfaces of adjacent modules mate to form fueltight joints at the bottom of said fuel chamber, and

iii. at least some of the said protruding areas engage the said opposing areas and hold apart other opposing areas of the external outlet surfaces of said adjacent module so as to form fuel outlet passages from said fuel chamber.

2. A burner according to claim 1, in which the external cross sections of the modules at the outlet and closure surfaces are conformable polygons.

3. A burner according to claim 2, in which the polygons are regular hexagons, rectangles, equilateral triangles or squares.

4. A burner according to claim 3, in which the protruding areas occur at the comers of polygonal tubes.

5. A burner according to claim 1, In which the protruding areas take the form of studs which project from nonprotruding areas.

6. A burner according to claim 1, in which the outlet surfaces have a series of protruding and nonprotruding areas arranged so as to produce tubes between the protruding areas.

7. A burner according to claim 1, which also comprises a surround within which the modules are mounted.

8. A burner according to claim 7, in which the surround comprises a fuel channel for conveying fuel around and into the fuel chamber.

lOlOlS 0340 

1. A diffusion flame burner for fluid fuels which burner comprises a plurality of juxtaposed individual tubular modules each of which has a. external outlet surfaces at one end for forming fuel outlet passages at said one end with external outlet surfaces of adjacent modules, b. external closure surfaces at the other end for forming fueltight joints at said other end with external closure surfaces of adjacent modules, c. a reduced diameter portion between the external outlet surfaces and the external closure surfaces of the module, providing a waist for forming a fuel chamber with the waists of adjacent modules, and d. a bore for conducting combustion air only through the module out of contact with fuel in said chamBer from a combustion air inlet zone at said other end to a combustion zone at said one end, at least some of the external outlet surfaces of the module having protruding areas for engaging opposing areas of the external outlet surfaces of an adjacent module, and the said tubular modules cooperating so that: i. the waists form a continuous fuel chamber around said modules between the external outlet surfaces and the external closure surfaces of said modules, ii. opposing closure surfaces of adjacent modules mate to form fueltight joints at the bottom of said fuel chamber, and iii. at least some of the said protruding areas engage the said opposing areas and hold apart other opposing areas of the external outlet surfaces of said adjacent module so as to form fuel outlet passages from said fuel chamber.
 2. A burner according to claim 1, in which the external cross sections of the modules at the outlet and closure surfaces are conformable polygons.
 3. A burner according to claim 2, in which the polygons are regular hexagons, rectangles, equilateral triangles or squares.
 4. A burner according to claim 3, in which the protruding areas occur at the corners of polygonal tubes.
 5. A burner according to claim 1, in which the protruding areas take the form of studs which project from nonprotruding areas.
 6. A burner according to claim 1, in which the outlet surfaces have a series of protruding and nonprotruding areas arranged so as to produce tubes between the protruding areas.
 7. A burner according to claim 1, which also comprises a surround within which the modules are mounted.
 8. A burner according to claim 7, in which the surround comprises a fuel channel for conveying fuel around and into the fuel chamber. 